U.S. families got fake orders to leave South Korea. Now counterintelligence is involved.

North Korean soldiers photograph Gen. Vincent K. Brooks, the commander of U.S. Forces Korea, in March as he visits the Joint Security Area inside the Korean Demilitarized Zone. (Photo by Sgt. 1st Class Sean K. Harp/ Army)

Army counterintelligence officials in South Korea are investigating fake mobile alerts and social media messages warning American military families and Defense Department personnel of orders to evacuate the volatile peninsula on Thursday.

U.S. Forces Korea “did NOT send this message,” officials said in a subsequent Facebook post. They warned that Americans living in South Korea with U.S. troops and Defense Department employees should confirm that any evacuation-related communications are legitimate before acting.

“Anyone receiving this false message should not click any links or open any attachments included in the correspondence,” the Facebook message said.

The U.S. military did not indicate who it thought had sent the phony messages, and it is unclear whether any military networks were compromised. An advisory issued by the Army and reported by Stars and Stripes urged people who have received the message to report it to an Army counterintelligence unit, which assess attempts by adversaries and their foreign intelligence services to exploit or access U.S. networks.

The fake warnings come at a sensitive time, as President Trump and North Korean leader Kim Jong Un trade insults and the United States presses the rogue regime to stop its nuclear weapons program. Such efforts have done little to rein in the dictator. On Friday, after the White House announced a new round of economic sanctions to further isolate the North, Kim — whom Trump has taken to calling “Rocket Man” — threatened to detonate a hydrogen bomb over the Pacific Ocean.

The U.S. military command in Korea routinely rehearses such evacuations, typically in the spring and fall. About 28,500 U.S. troops are stationed on the peninsula, along with thousands more family members.

“If a situation develops quickly and the Department of State requires assistance in the evacuation of noncombatants, the Secretary of State will request that the military assist in the evacuation,” the plan states. “During this stage, the military will assemble the noncombatants and then either relocate or evacuate them to a safer place.”

The Army advised that if an evacuation is ordered, Americans should carry with them irreplaceable documents, a first-aid kit, extra clothing, a flashlight and a blanket or sleeping bag. The service also recommends that families prepare a kit ahead of time that includes a backpack, legal documents, three days of food, bottled water, prescription medications, toiletries and a handheld radio.

“The Republic of Korea has the most heavily defended border in the world,” the plan said. “Though the probability of conflict remains low, the potential of hostilities occurring on the Korean peninsula is greater than in many other parts of the world.”